This invention relates to a head cleaning unit which is applied to an ink-jet printer performing printing with reciprocating a carriage provided with a printing head back and forth, in particular, to the cleaning unit for cleaning the printing head by sucking up waste ink from an inside and an outside of the printing head.
Generally, the ink-jet printer prevents the printing head from drying by covering an end surface of a nozzle (a nozzle surface) of the printing head by a cap when the ink-jet printer does not perform printing. Furthermore, the ink-jet printer removes the waste ink containing air bubbles and dust by a head cleaning unit. The head cleaning unit has a pump. The suck pump vacuums out a space between the nozzle surface and the cap so as to suck up the waste ink from the printing head to the space. The waste ink sucked up to the space is discharged through an ink-suck tube and the suck pump.
For example, such kind of head cleaning units are disclosed in Japanese Patent Unexamined Publications (JP-A) Nos. 259564/1992 and 300641/1997.
In a conventional head cleaning unit for the ink-jet printer, a nozzle surface of a printing head is covered with a cap. On one side of a bottom portion of a liquid room formed in the cap, an ink-suck hole for sucking up the waste ink from a nozzle through the liquid room is formed. On the other side of the bottom portion of the liquid room, an air-intake hole for sucking the air into the liquid room is formed. Furthermore, an ink-suck tube communicated with a suck pump is coupled with the ink-suck hole.
When the suck pump is driven, the liquid room is vacuumed into negative pressure so that the waste ink is sucked up from the nozzle of the printing head. On the other hand, the air is sucked up into the liquid room through the air-intake hole. Thus, the waste ink is sucked up (led) into the ink-suck tube through the liquid room together with the air from the air-intake hole.
However, if the conventional head cleaning unit mentioned above sucks up the waste ink with the suck pump driven, the unit cannot sufficiently suck up the waste ink so that the waste ink tends to be left at a slight space between the nozzle surface and the cap and corners of the bottom portion of the liquid room. This is because the only one ink-suck hole and the only one air-intake hole are formed on one and the other sides of the bottom portion of the liquid room, respectively. When the waste ink is left in the cap, the waste ink sticks on the printing head and soils the printing head. The waste ink stuck to the printing head drips onto a printing medium and soils the printing medium when the printing is performed.
Therefore, the waste ink tends to be left near the corners and border areas between a bottom surface and enclosure-walls limiting the liquid room of the cap. Furthermore, it is difficult to sufficiently remove the waste ink from the areas mentioned above by sucking.
Particularly, it is very difficult that such type of head cleaning unit provided with the only one ink-suck hole formed near the central area of the bottom surface of the cap sucks up the waste ink left in the areas mentioned above.
It is an object of this invention to deal with disadvantages mentioned above and to therefore provide a head cleaning unit for an ink-jet printer capable of sufficiently sucking up waste ink from a nozzle of a printing head and from a cap so as to prevent a nozzle surface from being soiled.
The other object, features, and advantages of this invention will become clear as the description proceeds.
This invention is directed to a head cleaning unit, applied to an ink-jet printer performing printing with driving a printing head, for cleaning the printing head by sucking up waste ink from the printing head, the head cleaning unit comprising a cap capable of covering with the printing head so as to contact with the printing head and vacuum means for generating negative pressure in a liquid room formed in the cap, the head cleaning unit cleaning the printing head by sucking up the waste ink from the printing head. The head cleaning unit further comprises an ink collector attached to the cap so as to contact with the cap. The cap is provided with a plurality of first ink-suck holes formed on a bottom surface of the liquid room so as to communicate the liquid room with a space limited between the cap and the ink collector. The ink collector is provided with a second ink-suck hole formed on a bottom surface adjacent to the space so as to communicate the space with the vacuum means. At least one of the cap and the ink collector is provided with an air-intake hole for providing air to the cap or the ink collector by the vacuum means. At least one of the first ink-suck holes is arranged along a contact area where the printing head and the cap are brought into contact with each other.